Plasma sprayed mullite coatings on silicon based ceramic materials

摘要

Coatings containing at least 85% by volume crystalline mullite with less than 15% by volume of amorphous material and mullite dissociation phases are plasma sprayed onto the surface of a silicon based ceramic substrate by closely controlling the plasma spray parameters including the mullite feed stock and its particle size, the nozzle outlet stand-off distance, movement of the substrate past the plasma flow, back side heating of the substrate and the powder feed rate through the plasma spray gun.